Okay, so!

I have had the IUD for almost 3 years ( mine lasts 5) and I have regular periods that’s last 5-7 days and they are pretty light! BUT this month I got my period a week early with very heavy bleeding and very bad cramping including in my back! (which I haven’t had since I got the IUD). Also to note, I am been sexually active with my boyfriend of 4 years! So now I’m really nervous and don’t know what to do? I did some research, and everything has said it could have been a really early miscarriage? Is that even possible? Is there a way to know for sure? Help me ease my anxiety!